The Greek cure for the fear of death had no side effects
Epicurus didn't try to make death less permanent. He tried to prove it isn't an experience at all.
Epicurus is remembered, unfairly, as the patron saint of indulgence — a man who taught people to chase pleasure. What he actually spent most of his energy on was talking people out of being afraid.
His argument against fearing death is almost insultingly simple: while you exist, death has not arrived, so it cannot touch you. Once it arrives, you no longer exist, so there's no one left for it to touch. There is no moment, he wrote to his student Menoeceus, in which you and death occupy the same room. It is, in his words, nothing to us.
This wasn't a debating trick. Epicurus built an entire ethics on removing needless dread — of gods who didn't care about human affairs, of an afterlife of punishment he thought didn't exist, of pain he believed was either brief or bearable. Later followers compressed it into four lines known as the tetrapharmakos, the four-part cure: don't fear god, don't worry about death, what is good is easy to get, what is terrible is easy to endure.
He wasn't selling comfort. He was doing subtraction, removing fears that had no evidence behind them, one at a time, until what was left was just a life.